/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2001, 2002,2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.dom;

import java.util.StringTokenizer;
import java.util.Vector;
import org.w3c.dom.DOMImplementationList;
import org.w3c.dom.DOMImplementationSource;
import org.w3c.dom.DOMImplementation;
import com.sun.org.apache.xerces.internal.dom.DOMImplementationListImpl;

/**
 * Supply one the right implementation, based upon requested features. Each implemented
 * <code>DOMImplementationSource</code> object is listed in the binding-specific list of available
 * sources so that its <code>DOMImplementation</code> objects are made available.
 *
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html#DOMImplementationSource'>Document
 * Object Model (DOM) Level 3 Core Specification</a>.
 *
 * @xerces.internal
 */
public class DOMImplementationSourceImpl
    implements DOMImplementationSource {

  /**
   * A method to request a DOM implementation.
   *
   * @param features A string that specifies which features are required. This is a space separated
   * list in which each feature is specified by its name optionally followed by a space and a
   * version number. This is something like: "XML 1.0 Traversal Events 2.0"
   * @return An implementation that has the desired features, or <code>null</code> if this source
   * has none.
   */
  public DOMImplementation getDOMImplementation(String features) {
    // first check whether the CoreDOMImplementation would do
    DOMImplementation impl =
        CoreDOMImplementationImpl.getDOMImplementation();
    if (testImpl(impl, features)) {
      return impl;
    }
    // if not try the DOMImplementation
    impl = DOMImplementationImpl.getDOMImplementation();
    if (testImpl(impl, features)) {
      return impl;
    }

    return null;
  }

  /**
   * A method to request a list of DOM implementations that support the
   * specified features and versions, as specified in .
   *
   * @param features A string that specifies which features and versions are required. This is a
   * space separated list in which each feature is specified by its name optionally followed by a
   * space and a version number. This is something like: "XML 3.0 Traversal +Events 2.0"
   * @return A list of DOM implementations that support the desired features.
   */
  public DOMImplementationList getDOMImplementationList(String features) {
    // first check whether the CoreDOMImplementation would do
    DOMImplementation impl = CoreDOMImplementationImpl.getDOMImplementation();
    final Vector implementations = new Vector();
    if (testImpl(impl, features)) {
      implementations.addElement(impl);
    }
    impl = DOMImplementationImpl.getDOMImplementation();
    if (testImpl(impl, features)) {
      implementations.addElement(impl);
    }

    return new DOMImplementationListImpl(implementations);
  }

  boolean testImpl(DOMImplementation impl, String features) {

    StringTokenizer st = new StringTokenizer(features);
    String feature = null;
    String version = null;

    if (st.hasMoreTokens()) {
      feature = st.nextToken();
    }
    while (feature != null) {
      boolean isVersion = false;
      if (st.hasMoreTokens()) {
        char c;
        version = st.nextToken();
        c = version.charAt(0);
        switch (c) {
          case '0':
          case '1':
          case '2':
          case '3':
          case '4':
          case '5':
          case '6':
          case '7':
          case '8':
          case '9':
            isVersion = true;
        }
      } else {
        version = null;
      }
      if (isVersion) {
        if (!impl.hasFeature(feature, version)) {
          return false;
        }
        if (st.hasMoreTokens()) {
          feature = st.nextToken();
        } else {
          feature = null;
        }
      } else {
        if (!impl.hasFeature(feature, null)) {
          return false;
        }
        feature = version;
      }
    }
    return true;
  }
}
